Impeller with center intake



Nov. 10, 1953 R. SEINFELD IMPELLER WITH CENTER INTAKE Filed Feb. 26, 1948 JNVENTOR. LUDW/K R. SE/NFELD d dwi ag ATTORNEY ?at ented Nov. iii,

IMPELLER WITH CENTER INTAKE Ludwik R. Seinfeld, New Providence Township, Union County, N. J., assignor to De Laval Steam Turbine Company, Trenton, N. J., a corporation of New Jersey Application February 26, 1948, Serial No. 11,097

1 Claim.

This invention relates to centrifugal pumps and has particular reference to improved impeller constructions therefor.

It is well known that open impellers are desirable for single suction pumps operated at high speeds. The diameters of such open impellers, however, are necessarily small because unreinforced vanes of large diameter impellers would flutter both during machining and during oporation. The conventional manner of reinforcing and balancing large diameter open impellers has involved extending the impeller hub into a circular or radial rib providing balancing holes in the rib opposite the impeller eye and providing narrow vanes at the back of the rib as viewed from the impeller eye. Balancing holes are adequate, however, to assure sufficient flow only for narrow vanes; but narrow vanes create high turbulence and therefore cause erosion and loss of head resulting in reduced hydraulic efficiency.

In accordance with the present invention high speed single suction impellers are constructed in such a way that the liquid entering the impeller eye is split into two streams while passing into the impeller, the streams not necessarily being equal in volume. This splitting is achieved by providing a circular rib of adequate strength to withstand the centrifugal forces of high speed of rotation as well as to reinforce the vanes of the impeller without being in direct contact with the impeller hub.

The foregoing general object of the invention as well as specific objects relating to details will become apparent from the following description read in conjunction with the accompanying drawing in which:

Figure 1 is a section illustrating the incorporation of the invention in a single suction impeller the vanes being shown in circumferential projection for clarity; and

Figure 2 is an elevation showing the inlet side of the impeller of Figure 1.

There is indicated at 2 the hub of an impeller 4 of single suction type which may be included in a conventional housing which is indicated by the construction lines 8 and I0. Discharge takes place into a conventional diffuser passage indicated at I2.

Vanes M are provided which are supported by an annular member I6 providing ribs between the adjacent vanes the edges ll of which serve to divide the inflowing stream into two portions flowing on opposite sides of these ribs. The ribs 16, as will be evident from Figure 1, provide for smooth guidance of the two flows adjacent to the walls 8 and ll! of the casing, the hub 2 being arranged as indicated at 20 to form contoured shrouds or side plates for short lengths between the radially inward portions of the backs of the vanes which guide the liquid, providing smooth flow in cooperation with the housing wall ii Balancing openings R8 are provided through the ribs It to equalize pressures at the front and back of the ribs, and provide improved hydraulic balance.

It will be seen that the axial extremities of the hub, vanes and annular member provide a central inlet for the fluid which then discharges from the periphery of the impeller.

The impeller thus constructed is particularly adapted for high speed boiler feed pump use. Maintenance of similar fiow conditions on both sides of the ribs is achieved and thereby the hydraulic efliciency is substantially improved with reduction of erosive conditions as compared with impellers heretofore constructed. It will be evident that the vanes are Well supported and consequently high speed operation may be achieved Without fluttering of the vanes or their destruction by centrifugal forces.

Desirably the construction is such that the volumes of liquid flowing on the two sides of reinforcing ribs are substantially equal but this is not absolutely essential. It will be noted that the inner diameter of the rib arrangement is smaller than the maximum diameter of the portion 20 of the hub 2 so that the two jointly provide shrouding for a portion of the path of liquid flow at the back of the rib.

It will be clear that various modifications of the invention may be made Without departing therefrom as defined in the following claim.

What I claim and desire to protect by Letters Patent is:

A centrifugal impeller of the high speed single suction type having a central inlet comprising a hub, radially and axially extending vanes carried by the hub, and annular means radially spaced from the hub and extending along the vanes and dividing the vanes axially of the impeller and providing ribs extending between the vanes, said ribs and vanes forming channels of dissimilar length on opposite sides of said annular member, the axial extremities of said hub, vanes and annular member providing the central inlet for said impeller, said ribs having portions extending axially toward said central inlet for splitting a stream of fluid entering the impeller, each rib being provided with a plurality of passages interconnecting said channels, said passages being disposed between the vanes and being arranged in radially spaced relation to the impeller axis at successively greater distances therefrom to permit pressure equalizing flow between said channels on opposite sides of said ribs at intervals at said successively greater distances.

LUDWIK R. SEINEELD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 445,919 Brown Feb. 3, 1891 Number Number 28,980

Name Date Orton July 28, 1896 McMurdie Mar. 14, 1916 Weil Aug. 5, 1924 McMurdie Sept. 13, 1932 Kiep et a1 Apr. 18, 1933 Bennett Aug. 5, 1947 FOREIGN PATENTS Country Date Great Britain A. D. 1911 

